4.0 Renix - Timing is off 180° but runs

[Big_Mark]

My timing gearset needs changing so I started working on it and discovered some weirdness, want to fix it but need to make sure I understand what is wrong and how to fix it. I would appreciate the input of the forum to back check me before I try to "fix" anything.

 

Before starting this project, aside from the clacking from the stretched timing chain, my engine has been running great. Mileage is normal and power is great.

 

I have replaced a few timing chains in my day, and my procedure has always been to “pop” off the timing cover (because it just pops right off easy, right?), turn the crankshaft until the timing gear dots align next to each other, pull gear and chain, replace them making sure the dots align.

 

 

The weird thing is, on my Jeep when I align the timing gear dots, my dizzy is off 180° (rotor sits at #6 position)

 

 

In this alignment, looking at the position of the Crankshaft from below, the #1 cylinder (front of Jeep) it appears to be Top Dead Center (TDC).

 

 

 

Since it runs fine in this condition, I am trying to decide if I want to fix, or just run it. I am leaning toward "fixing" as this has caused confusion in the past. When I swapped out my distributor and started indexing it last year, I discovered I had to rotate the distributor 180° to get the engine running but didn’t exactly know why and since it ran fine, I just shrugged my shoulders and ran with it.

 

Here is how it is currently timed

 

Turning the crank so the distributor is in the #1 position, the #1 cylinder is at Bottom Dead Center (BDC) and the crank timing gear dot is on the opposite side of the gear, but in alignment (180° off)

 

 

Dizzy Position

 

 

Crank Position

 

 

From what I can surmise, I think I have two things 180° out of rotation.

1.       Crank Shaft

2.       Distributor (to compensate for the Crank being out of timing)

 

Mystery questions:

How did/does my engine even run with the existing timing condition?

Is it firing in reverse order?

Does it matter?

I think the double 180° reversals are like a double negative, they cancel each other out and get it into correct timing. But it makes my head spin trying to figure it out.

 

DISCLAIMER: This is how I got the Jeep.  There was one bolt missing from the timing cover, so I suspect somebody in the past screwed this thing up when they replaced the timing ger set (?).

 

Since this is still all pulled apart, I’d like to fix it, BUT it is working, so I am trying to decide if I want to risk making matter worse or get it straightened out while its accessible, so here is where I need your help.

 

I am pretty sure I can fix this by:

From it's current condition, rotate the crank, so the dots align (to get the cam gear in correct position) this will put the crankshaft into BDC. Next step would be removing the timing gearset, rotate the crank so it sits at TDC, replace the timing gearset, ensuring the dots align next to each other. At this point the distributor should still be at #6 position so I will need to pull it out, rotate it 180° then make sure it is indexed properly. (I still have my cut cap from when I did this before).  Does this seem like the correct sequence to y’all?

 

Before I try to “fix” anything I ask the forum to back check my understanding of timing.

Please confirm that if these conditions are met that my timing should be sound (or at least set to zero)

 

1.       Both timing gear dots are next to each other

 

 

2.       Distributor is in #1 rotation/position

 

 

3.       #1 (front) cylinder is set at TDC

 

 

Final question: Does it matter if TDC is in the compression stroke, or exhaust stroke when I set the timing? I think it doesn't matter since anytime the dots align, the distributor will be at #1 index. Since one stroke of each cylinder is firing (compression) and the other is exhaust (non compressing) the ignition should sort this out on it’s own but I want to be sure before proceeding.

 

I know it’s early in the day and there are lots of 180°s here, so I appreciate your help. I do want to make this right before I button it up because hate leaving issues unresolved, especially since I can easily fix this now while I have it all apart!

 

Thanks in advance I look forward to your answers!

[Ωhm]

Yes, you can have the valvetrain off 180°, making the Distributor off 180° and the engine will run just fine, but now your SYNC signal is off 180°. Some will say the SYNC signal will correct itself every time you START and RUN your engine if that what you want.

 

2 hours ago, Big_Mark said:

Does it matter if TDC is in the compression stroke, or exhaust stroke when I set the timing?

 

Yes. TDC has two meanings. With timing you're looking for TDC during the Compression↑TDC↓Power stroke.

[Big_Mark]

Thanks @Ωhm 

Since I know there is a deficiency I am going to correct it otherwise it will eat at me.

To make sure I'm on the correct stroke at TDC I am going to pull of the valve cover so I can make sure #1 is compressing by visually inspecting the valve/rocker positions.

Oh the joys of being a Shadetree mechanic!. 

 

 

[Ωhm]

3 minutes ago, Big_Mark said:

Oh the joys of being a Shadetree mechanic!. 

 

[Big_Mark]

After pulling the valve cover, I’ve determined by observing the valve position and stroke based on the position of the distributor all is correct. if anything is 180 off, its the cam pin/sprocket . To rotate that would require switching the set pin to the other hole. That sounds like a recipe for disaster so I’m just going to run it as is. Afterall it works fine.

Maybe it was margarita Monday when my engine was assembled?

 I definitely overthought this whole process